In it he offers some excellent advice, but one particular design principle is worth heeding and has lots of implications, namely the API should be “explorable via a browser address bar.” This means several things (some of which he mentions, some of which he doesn’t):

Vinay does make some recommendations that preclude exploring the API in a browser, e.g. use JSON as the body content when creating resources with a POST. But there aren’t alternatives for POSTing content from a browser anyway, and using GET to create resources is bad bad bad.

If you do want to stay in the browser when POSTing to an API, then there are two great Chrome extensions you should check out: